function setCanvasStyle(map, size) {
    let canvas = document.createElement("canvas");
    let ctx = canvas.getContext("2d");
    canvas.width = size;
    canvas.height = size;
    /* 设置半径 */
    let radius = size / 4;
    /* 绘制 */
    let increase = true;
    /* 25~35 */
    function draw() {
        ctx.clearRect(0, 0, canvas.width, canvas.height)
        ctx.beginPath();
        ctx.arc(size / 2, size / 2, radius, 0, Math.PI * 2);
        ctx.closePath();
        ctx.fillStyle = "#ff2d51";
        ctx.fill()
        if (radius > 25) {
            increase = false;
        } else if (radius < 15) {
            increase = true;
        }
        if (increase) {
            radius++;
        } else {
            radius--;
        }
        setTimeout(draw, 50)
        /* render */
        map.render();
    }
    draw();
    /* 设置canvas元素为openlayers的样式 */
    let style = new ol.style.Style({
        image: new ol.style.Icon({
            img: canvas,
            imgSize: [canvas.width, canvas.height]
        })
    })
    return style;
}